Hello aspirant
Congratulations for getting 204 marks in upsee. Its very hard to give exact rank  as rank  of upsee vary every year based on different factor. One can predict expected rank  by analysing past year trends.

Factor affecting rank -
1. No of students
2. No of seats
3. Difficulty of paper
4. past year trends

You expected rank will be around 13- 15k obc category rank

Colleges you can get with this rank
1. Ucer Allahabad
2. United institute greater noida
3.Rkgit ghaziabad
4. GL bajaj
5. Nitra

You can get list of best college according to your rank using careers 360 college predictor tool

UPSEE (Engineering) College Predictor 2020 - Predict ...

UPSEE College Predictor - Know your College Admission Chances Based on ...

Hope this will help

Best of luck.